Where's the center of mass of the ring? What is the gravitational force on an increment of mass dm on the ring? What is the orientation of the normal to the plane of the ring to the direction of gravitational force on the ring's center of mass?

The ring is flat and circular, with a mass m, and a radius is r;
the ring is inclined at angle i to the z axis (like a moon's orbit, or the equator of the Earth);
and it can be rotated at angle along z axis: f.

The second mass M is placed at a distance d to the ring, and we can assume: d >> r, say: d/r > 100
And question is: what is a tidal torque due to the mass M action on the ring?